US2018270A - Fluid storage system - Google Patents

Description

Oct. 22, v1935. w, G, LAIRD 2,018,270

FLUID- STORAGE SYSTEM Filed June 15, 1931 2 Sheets-Sheet l INVENTOR J0 l. r waaura. Laird ATTORNEY Oct. 22, 1935. w. G. LAIRD 2,018,270

FLUID STORAGE SYSTEM Filed June 1s, 1951 2' Sheets-Sheet 2 Wilbur 6. Laird ATTORNEY Patented on. 22, 1935 UNITED STATES PATENT OFFICE STQBAGE SYSTEM Wilbur G. Laird, Pleasantvllle, N. 'Y., asslgnor to Doherty Research Company, New York, N. Y., a corporation-of Delaware Application June 15, 1931, Serial N... 544,48

8 Claim.

I When direct solar heat raises the temperature of liquid petroleum. and the contents of the vapor space within a sealed storage tank, the pressure within the tank may rise rapidly due to the evolution" of dissolved gases and evaporation of the volatile fractions of the oil and the expansion of the gaseous contents of the vapor space above the liquid. The pressure'within an oil storage tank, thus exposed to solar evaporation and expansion, if not-immediately corrected, as by releasing vapors to the atmosphere, may attain such proportions that the tank may burst. Moreover under conditions where. the temperature of the surrounding atmosphere drops rapidly, the pressure within a sealed storage tank may drop below atmospheric due to the condensation and contraction of vapors and gases. In such a case thepressure withinthe tank may drop to the point where the walls or the roof thereof will collapse.

It has been proposed to overcome these difliculties and at the same time prevent vapor loss I and reduce danger from fires as a result-of admetal which will withstand only very low presmission of air into the tank, byconnecting the vapor space of a sealed oil storage tank in closed circuit with a variable volume gasholder, so that the pressure within the tank may be controlled by free breathing or vapor flow between the tank and the gasholder. However it is often impracticable to provide *bipes connecting the storage tank and gasholder of sufliclent capacity to allow the rapid breathing which would sometimes be required to prevent development of abnormal sure differentials between the surrounding atmosphere and" the inside of the tank. This type of tank roof maynot always have suflicient in- I invention;

herent strength to withstand the pressure. amounting to several inches of water, which is imposed by a gasholder lift on a closed vapor storage system such as described in my U. S.

Patent 1,794,383. The strongest section of such 5 tanks is at their bottom curb, such curb being designed to withstand the hydrostatic pressure of the body of oil stored.

One object of the present invention is to provide a system of reinforcement for the common 1 type of cone-roofed oil storage tank whereby a large tank may be strengthened to withstand pressurevdiflerentlals up to several ounces between its interior and the outside atmosphere.

A feature of the tank reinforcement provided 15 by the present invention is that it is simple in design and economical to install, enabling the use of previously erected cone-roofed storage tanks ina vapor conservation system such as that described in my said Patent No. 1,794,383, II

at a fraction of the cost that would be involved in rebuilding the roof in stronger form or in replacing such tanks with new tanks of suitable strength and storage capacity.

Another object of the present invention is to ll provide an improved type of safety valve adaptable to a closed liquid storage system to correct any abnormal pressures developed within the system.

Other objects and advantages of the invention 30 Q will be apparent from the following detailed description, taken with the accompanying drawings, in which:

Fig. 1 is a view in diagrammatic vertical section of'a liquid storage system embodying the improvements forming the subject of the present Figr 2 is an enlarged diagrammatic top plan view of partof the roof of the oil storage tank shown in Fig. 1,-parts being brokenaway to show the construction of underlying parts;

Fig. dis a detailed-view illustrating one way of assembling the rods preferably used according to the present invention for reinforcing the oil storage tank Fig. 4 is a vertical sectional view of the preferred safety valve element of the improved oil storage system, parts being in elevation:

Fig. 5 is a top plan view of the safety valve shown in Fig, 4; and 50 "Fig. 6 is an enlarged vertical sectional view of a portion of the valve actuating mechanism shown in Fig. 4, illustrating the operation of. the mechanism due to excessive pressure within the system I Referring to the drawings (Fig. 1), the liquid to be stored is placed in a storage tank I6 having cylindrical walls I2'and a conical roof I6 tightly sealed against the escape o; gases and vapors. The roof I4 .02 the storage is reinforced by channel beams I6 which are preferably placed on top of the roof in radially extending spaced relationship and which act to maintain the roof rigid under interiortank pressures that would tend to buckle the ordinary type of unreinforced conical roof.

Attached toeach channel I6 at the approximate midpoint thereof, are brackets I6 (Fig. 3) which together with the channel beam I6 support a plate 26. An adjustable eye-bolt 22 extends through the plate 26 and roof I4, and is pivotallyconnected to the approximate midpoint of a pivotal pin plate 24 located within the tank I6. A tension reinforcing member in the form of an eye bolt or rod 26 is pivotally connected to plate 24 and extends to a bracket 26 attached to a plate 66 located at the bottom curb 62 of the tank I6. with which the rod 26 is in adjustable engagement. From the other end of the plate 24 a pivotally connected rod 64 extends and is in adjustable engagement with a bracket. 66 attached to a center plate 66. Although the tank reinforced according to the present invention may not have a central roof support, the center plate 66 may-have a central opening as .at 46 and may be separable so as to encircle a center post, if it is desired to; apply the tank reinforcement to a storage tank which is equipped with a center roof support.

The system of reinforcement as described in connection with the tying of the roof by reinforcing members to the bottom curb of the tank, may be similarly applied to any number of a pluralityof channel beams I6. each pivotal J plate 24 having reinforcing rod connections extending to thebottom curb of the tank and to the centrally located plate 66 within the tank. The center plate 66 obviates the necessity of the horizontal ,tie rods crossing at a common point in the center of the tank.

Such a tank reinforcing system is completely adjustable by means of the nuts-on the rods 22, 26 and 34. By means of these nuts the entire reinforcing system may be firmly and rapidly installed. The eye bolts 22 may be packed, or welded to the roof, at the point where theypass therethrough, to prevent leakage, and the roof may thus be permanently'reinforced so as to pletely illustrated withstand pressure differentials up to several ounces between the interior of alarge tank and the outside atmosphere.

The vapor space of the storage tank I6, rein-. forced as above described, is connected by means of a vapor conduit 42 to a safety valve 44 suitably mounted upon ;the roof of the tank I6 by. means of leveling brackets, and thence-by means of a vapor conduit 46 to the bell of a variable volume gasholder 46 (Fig. 1). While but one oil storage tank is shown as being connected to the bell of the gasholder 46, it is obvious that a series of interconnected oil storage tanks may be connected to the gasholder 46 in a system such as described in my Patent No. 1,794,383. 1

The safety valve 44, the application of which according to the oil storage system of the present invention is shown in Fig. his more comin Flgs.4, 5, and 6 of the drawings.

The valve 44 comprises a chamber "having a vapor inlet 62 from pipe 62, a mmoutlet pipe 64 formed as an extension of the vapor conduit 46, and a normally closed outlet pipe 66 leading to the atmosphere through openings 66 which are situated beneath, and protected by, a frusto-conicalv cover 66. Within the chamber 66 is a pair of buckets 62 and "64, each having knife edge trunnions 16 on opposite sides of its rim with which the ends of beams 66 and 66 pivotally engage. The beams-66 and 66 are pivotaily mounted at their midpoints upon a shaft 10 I2 which is in turn pivotally supported by brackets. I3 afllxed'to opposite walls of chamber. 66. The buckets 62 and 64 are mounted in unbalanced weight relationship to each other. The beam end having the bucket 62 and its restraining rod is the heavier and is normally held in an elevated position in sealing relationship with the outlet pipe 66. The bucket 64 is shown in its'normally depressed position, allowing free flow of vapor iiireiigh the outlet pipe in '(Fig. 5). When the 2 0 bucket 62 is lowered, there is open communicae-e tion between chamber 66 and the atmosphere through the pipe 56. Bodies of liquid I4 and I6, which may be water in the summer and oilin the winter, are maintained in the buckets 62 and 64, respectively, so as to act as sealing liquid when the buckets 62 and 64 are in sealing engagement with the respective pipes 66 and 64. Above the chamber 66 is located a diaphragm chamber 16 which contains a common form of so movable diaphragm 66 dividing the chamber I6 into two compartments 62 and 64. The compartment 82 communicates with the chamber 66 through a conduit 66 and 66, and the compartmeat 84 communicates with the atmosphere as through port 66. A- branch is provided from the conduit 66 and is valved at 62 to permit attaching a gauge to determine the pressure within the system. A valve is'providedat 64 in conduit 66 for the purpose of closing off communica- 4o 7 tion between chambers 66 and 16, should discontinuance of the operation of the safety valve be desired.

i The diaphragm 66 operates the rod 66. which moves upwardly or downwardly as the pressure within the tank- I6 and chamber 66 changes. The rod 66 is slidably attached to the double bellcrank 66, the T-ends of whichare in turn slidably attached to the slotted ends of bars I66 and I62. The bars I66 and I62 are pivotally secured to by pins to a latch I which is inturn pivotally connected to a bracket I66 extending upwardly from the cover 66. The double bell-crank 664s fulcrumed by, and attached to, a shaft I66 which isjournaled in brackets 6 extending mar-div 66 from the diaphragm chamber. I6.

' On the shaft I66 a member H2 is mounted so as to actuate with the shaft I66 in response to movements of the diaphragm 66. Upon upwarddiaphragm movement the member I I2-comes into contact with and raises the lever arm II4, which is loosely pivoted upon the shaft I66. A oounterweightJ I6 is adjustably mounted on the free end of lever arm I I4 toj'counteract the pressure under the diaphragm so until a pre-determined or I pressure is reached. The lever arm III, under.

normal pressure conditions within the system, rests upon a rest bracket III. Similarly on another part of the'shaft I66 is mounted a'member I26 whichactuates with the 70 shaft I66 in response to movements of the d iaphragm 66 caused by pressurechanges within the system. With downward diaphragm movement, the member I26 comes into contact with and-raises the lever arm I22. Lever arm I22 is76 loosely pivoted upon the shaft I03. and 'a. counterweight I24 is adjustably mounted thereon, to counteract the pressure above the diaphragm 80 until a predetermined pressure is reached. The lever arm I22 may be bent at the outer or free end thereof to form a vertical extension I26 adapted to rest upon the casing of the chamber 50 under normal conditions.

Attached to the bucket 62 and extending vertically upward through-the top of the frusto-conical cover 60 is a rod i28 notched at I30 and carrying at its upper end a collar I32 (Fig. 5). The latch I04 normally engages the notch I30 and maintains the rod .428 in a raised position. In this position the bucket 62 containing the body of sealing liquid 14, seals off communication between valve chamber 50 and the outer atmosphere thru pipe 56. t

The valve mechanism thus described is intended merely as a safety valve, and hence under normal conditions will remain in the position illustrated in Fig. 5., However under rapid temperature changes, or for other cause, the pressure within the system may occasionally vary beyond the pressure limits for which the valve is set. When the pressure within the tank I increases, the pressure within the chamber 30 and in the communicating compartment 82 of the diaphragm chamber III will increase accordingly and tend to lift the. weighted diaphragm 80. The counterweight H4 is adjustable on the lever II4 to restrain the upward movement of diaphragm 80 until a predetermined limiting pressure has been reached. Whenthls limiting pressure is reached, the diaphragm 30 will rise and lift the arm 98 of the double bell crank which is attached to the shaft I08, and, by means of member II2, will lift the lever arm 4 and the counterweight H6, In this movement the arms I00 and I02 of the double bell crank will be actuated as shown in Fig. 6, and the latch I04 will be disengaged by meansci bar I02 from the notch I30 in the rod I28, allowing the heavier bucket 62 with its retaining rod I23 to fall. As bucket 62 falls, beams 68 and 33 swing on the bearings 13 and bring the bucket 64 into sealing relationship with the pipe 54, thus sealing of! this outlet pipe and simultaneously opening the chamber 50 to the outside atmosphere through the pipe 56 and the openings 38.

similarly, when the pressure within the system decreases, the pressure within the chamber 50 and the compartment 02 of the diaphragm chamber will decrease accordingly and the diaphragm 80 will tend to fall. The counterweight I24 is adjustable on the lever arm I22 to restrain the downward movement of diaphragm 30 until a preto lift the lever arm I22 and counterweight I24.

In this movement the upper arm of the double bell crank will disengage the latch I04 from the notch I30 by means of bar I03, allowing the bucket 62 to fall and eflect simultaneous sealing of the pipe 5,4 and the opening of chamber to to latch I34 (Fig. 6), which is pivotally mounted on a bracket I36 extending upwardly from the cover". The latch I34 is normally held in an approximately horizontal position (Fig. 4) by spring I38 extending from the bracket I36 to the arm I34. Normally latch I34 engages the pin I40 attached to the shaft of the counterweighted flag arm I42 which is held in an approximately horizontal position. At one end of the flag arm I42 is a flag or other symbol I44 overbalanced at theother end by a weight I46. When the collar I32 trips the latch I34, the signal arm I42 is released and swings to a vertical position so that the flag may notify the operator that the pressure on the system has exceeded the set limits, and has tripped the safety valve, cut the tank ofl of the system, and vented it to the atmosphere.

The safety valve is designed for manual re setting, and may be manually tripped when it is desired to disconnect an oil storage tank from the system.

The invention having been thus described, what is claimed as new is:

1. A fluid storage system comprising a normally sealed oil storage tank, a variable volume gasholder, a breather line communicably connecting the gas space at the top of said tank and said I holder, and a safety valve connected in said breather line having mechanism operably responsive to variations of pressure within. said system from a predetermined maximum and a predetermined minimum for simultaneously cutting oil communication between said tank and said holder and breaking the seal between said tank and atmosphere. t5

2. In a petroleum storage system, a sealed oil ;storage tank having upright cylindrical walls and the roof of said tank and its bottom curb and strengthening the same against press'uresim- 45 pressed thereon by said holder lift, and a safety valve having a normally closed relief conduit incorporated in said breather line to compensate for any lack of breathing capacity during periods of abnormal pressure change in said system, said 4 safety valve including mechanism responsive to abnormal pressures within said system operative to break the seal on said relief conduit and to close said breather line.

3. In a. petroleum storage system, a sealed oil storage tank having upright cylindrical walls and a conical'roof, a variable volume gas holder of the movable lift type, a vaporbreathing line communicably connecting the top of said tank and said holder and forming therewith a. vapor breathing system and reinforcing members connecting points intermediate the peak and periphery of thereof of said tank and its bottom curb and strengthening the same against pressures impressed thereon 'by said holder lift.

4. A reinforced liquid storage tank havingcylindrical walls and a conical roof, the periphery of which is attached to the upper edges of said cylindrical walls-said roof being reinforced by a series of beams attached thereto intermediate the peak and the periphery thereof, and by tension members connecting said beams and the lower portion of said tank walls.

5. A reinforced liquid storage tank having cylindrical walls and a conical roof, reinforcing fl iromthepeaktotheperipheryoisaidroonand tie rods extending diagonally from points intermediatethepeakandperipheryottheroot.to

thebottomq boisaidtank.

8. A reinforced liquid storage tank having cylindrlcalwalisahdaconicalMOLandreiniorcingiorsaidrooicomprismgaseriesottension rods of adjustable length extending diagonally from spaced radial points intermediate the peak andperiph'ery of said to m me. around the bottom curb. 7. A liquid s tank walls and a conical root, rigid reinforcing members attached to said root termediate the peak and peripherythereof, and a plurality of tension members extending from said-relniorcin'g members to pivotalplatesandtrom'saidplatestothe bottomcurboisaidtankwalisandtoa-plate centrally located within said tank.

8.Inapetroleumstoragesystem.asealedoil mtanhavariahlevolumegas m breathing iine communicablythetopoisaidtankandsaidholderandiorming therewith a vapor breathing system. a safety-- valvohaving a normally closed reliei conduit liquidseal bucket valveavthe heavier of 10 which is mounted in normal closing relationship withsaidreiieiconduitandtheotheroiwhich bucket valves is adapted to close the normally 'openbreathinglineconnectlngsaidtankand we to abnormal pressures within said system ior actuating said bucket valves simultaneholder, 'said satety valve including mechanism is responsi -0ilsly-t0break'thesealm1drel1ef00ndiiitand' to close we breather line.

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